1. Technical Field
The present disclosure relates to an optical device and an image display device.
2. Related Art
To increase the resolution of an image to be projected to a value more than the resolution of an optical modulation device of a liquid crystal panel, an axis of an image light emitted from the optical modulation device can be shifted. As an example, JP-A-2011-158589 describes an optical path control device that shifts an axis of an image light. The optical path control device described in JP-A-2011-158589 includes a glass plate, a moving section that holds the glass plate, a support section that supports the moving section, and a pair of plate springs that couples the moving section to the support section. A posture of the glass plate is changed by swinging a retention member by using the plate spring as a rotation axis. Accordingly, the light (image light) which is incident on the glass plate is deflected, and the axis is shifted. To reduce unwanted vibration of a holding member, the optical path control device of JP-A-2011-158589 configures a drive signal as a wave in which a sine wave is connected between a maximum value maintained for a predetermined time and a minimum value maintained for a predetermined time.
However, if the drive signal is used, an image, which is displayed, is degraded due to factors different from unwanted vibration. For example, to display a sharper image, a maintenance time of the maximum value and a maintenance time of the minimum value is increased during a unit period. However, in the drive signal of JP-A-2011-158589, the maximum value and the minimum value are connected by a sine wave and, thus, the maintenance times of the maximum value and the minimum value during a unit period are short thereby affecting the displayed image. In addition, the moving section vibrates on the opposite side once (at a moment) by the sine wave that connects the maximum value to the minimum value and, thus, the image light is blurred.